How Redistricting Works

Redistricting is the process of redrawing voting district lines to reflect population changes. It’s an important part of our democracy.

In Pennsylvania and most other states, this process happens every 10 years, after each U.S. Census. This means that after the 2020 census is completed, new lines will be drawn for several types of voting districts:

Congressional districts, which define who represents you in the U.S. House of Representatives. There are currently 18 congressional districts in Pennsylvania.

State legislative districts, which define who represents you in the PA Senate and PA House. Based on where you live, you’re assigned to two state legislative districts: a PA Senate district and a PA House district. There are currently 50 PA Senate districts and 203 PA House districts.

When you vote, it’s for representatives within your assigned districts—that’s why they’re sometimes called voting districts. But your district matters just as much beyond Election Day: When you want to speak up about an issue or ask for help with a government service, you’ll go to your elected representatives within your assigned districts.

Why redistricting happens

The redistricting process is complicated, but you don’t have to be a politician or a policy wonk to understand the basics. Here’s what you need to know.

In the United States, representation is based on population: the more people in an area, the more representatives it gets (except in the U.S. Senate, where each state gets two senators, no matter what). As populations change and move around, we need to update the size and shape of districts, so each lawmaker continues to represent a fair portion of the population.

In 1964, the Supreme Court ruled that this practice is mandated by the constitution. That case, Reynolds v. Sims, involved Alabama, which hadn’t redistricted for 60 years. In that time, urban districts had grown significantly—resulting in more representatives per rural voter than per urban voter. The Supreme Court ruled that the Equal Protection Clause of the 14th Amendment of the Constitution requires that voting districts be equal in population. Chief Justice Warren wrote in the majority opinion that “legislators represent people, not trees or acres” and “legislators are elected by voters, not farms or cities or economic interests.”

Because of this ruling, most voting districts are now drawn to be equal in population. But that alone doesn’t make them fair—because how those new lines get decided still isn’t equal.

The redistricting process

Article 1, Section 4 of the Constitution gives the states primary authority to regulate federal elections, including congressional redistricting. However, it also states that Congress is the ultimate authority, and may supersede state laws. Congress has exercised this authority—for example, to require single-member districts (instead of multi-member districts) and to enhance racial and ethnic minority groups’ representation—but it has never mandated specific procedures for redistricting, despite many bills that have been introduced.

Congressional redistricting

Congressional redistricting starts with reapportionment. Because the U.S. House of Representatives always has a total of 435 seats, the country must always be divided into 435 congressional districts. But some states are growing, while others aren’t. Reapportionment is the process of adjusting how many of those 435 seats each state should get, depending on how the country’s population has changed since the last census. The quickest-growing states gain House seats—which forces states with flatter populations to lose seats.

Because Pennsylvania’s population increased much more slowly than some other states’ between 2000 and 2010, Pennsylvania lost one House seat after the last census, and we’re projected to lose one or two more in 2020.

After districts are reapportioned to each state, the lines need to be redrawn so that each district has roughly the same number of people living in it. All states have to be redistricted to account for population shifts, but states that have gained or lost seats—like Pennsylvania—tend to undergo the greatest changes. This is one of the reasons we’re such a target for gerrymandering.

Congressional redistricting is then done through the regular legislative process: a bill defining the district boundaries is passed by both the PA House and Senate and signed by the governor. The problem is, Pennsylvania law doesn’t mandate how congressional districts should be redrawn or what criteria should be applied to ensure new district boundaries are fair. Instead, the majority party can draw maps any way it pleases, and, depending who’s in the governor’s office, can end up with exclusive control over the result.

State legislative redistricting

PA House and Senate districts are referred to as state legislative districts. Article II, Section 17 of the Pennsylvania Constitution mandates that these districts be drawn by a five-member commission. Four of these are the majority and minority leaders of the PA House and Senate. These four then select a fifth member to serve as the commission chair. If the four cannot agree, then the PA Supreme Court appoints a chair.

This commission has exclusive authority to draw the maps. Article II, Section 16 of the Pennsylvania Constitution requires these districts “be composed of compact and contiguous territory as nearly equal in population as practicable” and to avoid dividing a “county, city, incorporated town, borough, township or ward” unless absolutely necessary.

The legislature does not vote on the commission’s plans, and the governor has no power to sign or veto them—only a citizen can file a appeal to the Pennsylvania Supreme Court. This gives party leaders enormous power over rank-and-file members of their respective caucuses: if a member proves to be too independent, they may be punished, usually by drawing them out of a “safe” district into one dominated by the other party. It also lets incumbent legislators draw their own districts—a clear conflict of interest from the start.

Local redistricting

Some municipalities must also conduct redistricting if representation on their legislative bodies is done by district, as opposed to at-large representation, where all the members are elected by the entire voting population of the political entity.

Some local governing bodies have delegated redistricting to outside groups, but retain final authority to approve any redistricting plan.

Local redistricting is covered by Article IX, Section 11 of the PA Constitution, which states that within a year of the census being officially reported, “each municipality having a governing body not entirely elected at large shall be reapportioned by its governing body or as shall otherwise be provided by uniform law, into districts which shall be composed of compact and contiguous territory as nearly equal in population as practicable, for the purpose of describing the districts for those not elected at large.”

It’s time for change

Currently, the only way to fight for fairer districts is with lawsuits. The 2010–11 redistricting process resulted in multiple lawsuits that cost Pennsylvania millions of dollars in legal fees and caused confusion among voters and election officials waiting for appeals to be decided.

In one lawsuit, plaintiff Amanda Holt demonstrated with three alternative redistricting maps that numerous counties, municipalities, and wards were needlessly split, leading to a Pennsylvania Supreme Court decision that the 2011 final reapportionment plan was contrary to law.

Fair Districts PA advocates amending the PA Constitution to establish an independent citizens commission, which will not only help create fair districts but also avoid costly and confusing lawsuits.